1. Field of the Invention
The present invention relates to a method of detecting a fault in a switching electricity source, and to a corresponding electricity source.
The invention is applicable to various types of device and in particular to drivers for controlling actuators of the torque motor or solenoid type, for regulating rotary machines, for switched mode power supplies, . . . .
2. Brief Discussion of the Related Art
Such devices generally make use of an electricity source that implements control of the pulse width modulation (PWM) type.
The electricity source has a control stage and a power stage. The control stage receives a setpoint signal and delivers to the power stage a control signal that is modulated with a predetermined duty ratio. The power stage is connected to a load to which it delivers electricity corresponding to the control signal. For this purpose, the power stage may comprise for example at least one chopper transistor controlled by the control signal.
In certain applications, in which a failure of the control device could have consequences that are considered to be critical, one of the main concerns is detecting faults and preferably identifying failed components.
It is thus known to detect a fault by measuring the voltage and the current at the hot point at the output from the power stage and by measuring the current at the cold point of the output of the power stage. This makes it possible to detect a short circuit in the load (the measured currents are equal to the setpoint current and the voltage is zero), an open circuit in the load (the measured currents are zero whereas the voltage is not zero), and a failure of the electricity source (the measured currents and voltage are zero even through the setpoint signal does not correspond to zero current). This requires relatively complex fault detection logic that is relatively expensive to implement.